Scheduling apparatus and scheduling method

ABSTRACT

A scheduling apparatus and a scheduling method, wherein the amount of signaling for frequency resource allocation information can be reduced while maintaining system throughput performance. In a base station apparatus ( 100 ), a scheduling section ( 113 ) allocates frequency resources to frequency allocation target terminals based on set frequency allocation units, and a frequency allocation parameter setting section ( 112 ) adjusts the set frequency allocation units set in the scheduling section ( 113 ) based on cluster numbers. Due to this, in each cluster number, frequency resources can be allocated based on the most suitable frequency allocation units with respect to the signaling bit number. As a result, the amount of signaling for frequency resource allocation information can be reduced. Further, system throughput can be maintained by making the cluster number, which is a parameter having little effect on system throughput, a setting parameter for frequency allocation units.

TECHNICAL FIELD

The present invention relates to a scheduling apparatus and a schedulingmethod.

BACKGROUND ART

For an uplink channel of 3rd generation partnership project long termevolution (3GPP LTE), a data signal of each terminal is assigned tocontiguous frequency bands to reduce the cubic metric (CM) and thepeak-to-average power ratio (PAPR). Transmission using these contiguousfrequency bands may be called “contiguous frequency transmission.”

A terminal transmits data according to a frequency resource assignmentinformation reported by a base station. Frequency resource assignmentinformation for contiguous frequency transmission involves twoinformation about a start position and an end position (or a bandwidthfrom a start position) in a transmission band. Therefore, when thesystem bandwidth is expressed as NRB [RB], the number of signaling bitsof frequency resource assignment information can be represented byequation 1 below. That is, because the number of candidates for a startposition and an end position in a transmission band can be expressed asN_(RB) (the numbers of both ends and borders between adjacent two RBs ina frequency band)+1, signaling bits are required for the numbers ofcombinations to select two candidates for a start position and an endposition in the frequency band out of the number of candidates N_(RB)+1,in equation 1.[1]The number of signaling bits=┌ log₂(_(N) _(RB) ₊₁ C ₂)┐[bits]  (Equation1)where a resource block (RB) is a unit for assigning frequency to data.One RB is formed with 12 subcarriers. When NRB=100 [RB] is satisfied,the number of signaling bits is 13 [bits].

For an uplink channel of LTE-Advanced, which is an evolved version of3rd generation partnership project long-term evolution (3GPP LTE), using“non-contiguous frequency transmission” in addition to contiguousfrequency transmission is under consideration to improve the sectorthroughput performance (see Non-Patent Literature 1).

Non-contiguous frequency transmission is a method of transmitting a datasignal and a reference signal by assigning such signals tonon-contiguous frequency bands, which are dispersed in a wide range ofband. As shown in FIG. 1, in non-contiguous frequency transmission, itis possible to assign a data signal and a reference signal to discretefrequency bands. Therefore, in non-contiguous frequency transmission,compared to contiguous frequency transmission, the flexibility inassigning a data signal and a reference signal to frequency bands ineach terminal increases. By this means, it is possible to gain greaterfrequency scheduling effects.

Here, as a method of reporting frequency resource assignment informationfor non-contiguous frequency transmission, there is a method ofreporting whether or not to perform assignment for each RB in the systemband, using a bitmap (see Non-Patent Literature 2). As shown in FIG. 2,a base station reports whether or not to assign the resource perpredetermined frequency assignment unit [RB] (per 4 [RB] in FIG. 2),using one bit. That is a base station reports to a terminal to whichfrequency is assigned, a frequency assigning bit sequence that isobtained by assigning the bit value of 1 to the former and assigning thebit value of 0 to the latter of the assignment sub-band that is assignedto a terminal to which frequency is assigned and the non-assignmentsub-band that is not assigned, in a plurality of sub-bands that areformed by dividing the system band per frequency assignment unit [RB].In FIG. 2, the frequency assignment unit to which bit “1” is assigned isa frequency area that is assigned to a terminal to be assigned while thefrequency assignment unit to which bit “0” is assigned is a frequencyarea that is not assigned to the terminal to be assigned. Therefore,when expressing a system bandwidth as N_(RB) [RB] and a frequencyassignment unit as P [RB], the number of signaling bits required for thefrequency resource assignment information of this method can berepresented by equation 2 below.[2]The number of signaling bits=┌N _(RB) /P┐[bits]  (Equation 2)

CITATION LIST Non-Patent Literature

-   NPL 1-   3GPP R1-090257, Panasonic, “System performance of uplink    non-contiguous resource allocation”-   NPL 2-   3GPP TS36.212 V8.3.0. 5.3.3.1.2 DCI format 1 type 0, “E-UTRA    Multiplexing and channel coding (Release 8)”-   NPL 3-   3GPP R1-084583, Panasonic, “Comparison between Clustered. DFT-s-OFDM    and OFDM for supporting non-contiguous RB allocation within a    component carrier”

SUMMARY OF INVENTION Technical Problem

However, non-contiguous frequency transmission has a problem that thenumber of signaling bits required to report frequency resourceassignment information increases compared to contiguous frequencytransmission. For example, when N_(RB)=100 [RB] and P=4 [RB] aresatisfied, the number of signaling bits is 25 [bits]. Although it ispossible to make an RB assignment unit (P) larger to reduce the numberof signaling bits, if the RB assignment unit is simply made larger,flexibility of frequency scheduling decreases, consequently damaging thesystem throughput.

It is therefore an object of the present invention to provide ascheduling apparatus and a scheduling method for making it possible tomaintain system throughput performance and reduce the amount ofsignaling for frequency resource assignment information.

Solution to Problem

A scheduling apparatus according to the present invention employs aconfiguration to have a frequency assignment setting section that sets afrequency assignment unit based on the number of clusters to apply to aterminal to which frequency is assigned; and a scheduler that assigns afrequency resource to the terminal to which frequency is assigned, basedon the set frequency assignment unit.

A scheduling method according to the present invention employs aconfiguration to set a frequency assignment unit based on the number ofclusters to apply to a terminal to which frequency is assigned; andassign a frequency resource to the terminal to which frequency isassigned based on the set frequency assignment unit.

Advantageous Effects of Invention

According to the present invention, it is possible to provide ascheduling apparatus and a scheduling method for making it possible tomaintain system throughput performance and reduce the amount ofsignaling for frequency resource assignment information.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 shows non-contiguous frequency transmission;

FIG. 2 shows a method of reporting frequency resource assignmentinformation for non-contiguous frequency transmission;

FIG. 3 is a block diagram showing a configuration of a base stationapparatus according to Embodiment 1 of the present invention;

FIG. 4 is a block diagram showing a configuration of a terminalapparatus according to Embodiment 1 of the present invention;

FIG. 5 shows an example of a table showing correspondence of a pluralityof numbers of clusters and frequency assignment units corresponding toeach number of clusters;

FIG. 6 shows a relationship between the maximum number of clusters thatcan be transmitted by a terminal apparatus and the average sectorthroughput;

FIG. 7 shows a method of determining a frequency assignment unitcorresponding to each number of clusters;

FIG. 8 shows an example of a table showing correspondence of a pluralityof numbers of clusters and frequency assignment units corresponding toeach number of clusters;

FIG. 9 is a block diagram showing a configuration of a base stationapparatus according to Embodiment 2 of the present invention;

FIG. 10 shows an example of a table showing correspondence of aplurality of numbers of clusters and frequency assignment unitscorresponding to each number of clusters;

FIG. 11 is a block diagram showing a configuration of a terminalapparatus according to Embodiment 2 of the present invention;

FIG. 12 is a block diagram showing a configuration of a base stationapparatus according to Embodiment 3 of the present invention;

FIG. 13 shows offset information for tune-adjusting a frequencyassignment position:

FIG. 14 shows an example of a table showing correspondence of aplurality of numbers of clusters and frequency assignment unitscorresponding to each number of clusters;

FIG. 15 shows an example of a table showing correspondence of aplurality of numbers of clusters and frequency assignment unitscorresponding to each number of clusters;

FIG. 16 shows an example of a table showing correspondence of aplurality of numbers of clusters and frequency assignment unitscorresponding to each number of clusters; and

FIG. 17 shows an example of a table showing correspondence of aplurality of numbers of clusters and frequency assignment unitscorresponding to each number of clusters.

DESCRIPTION OF EMBODIMENTS

Now, embodiments of the present invention will be described in detailwith reference to the accompanying drawings. In embodiments, the sameparts will be assigned the same reference numerals and overlappingexplanations will be omitted.

Embodiment 1

FIG. 3 is a block diagram showing a configuration of base stationapparatus 100 according to Embodiment 1 of the present invention. InFIG. 3, base station apparatus 100 is provided with RF reception section101, demultiplexing section 102, DFT sections 103 and 104, demappingsections 105 and 106, channel estimation section 107, frequency domainequalization section 108, IDFT section 109, demodulation section 110,decoding section 111, frequency assigning parameter setting section 112,scheduling section 113, encoding section 114, modulation section 115,and RF transmission section 116.

RF reception section 101 performs reception processing, such asdown-conversion and A/D conversion, on a signal received from terminalapparatus 200 (described later) via an antenna, and outputs thereception-processed signal to demultiplexing section 102.

Demultiplexing section 102 demultiplexes the signal input from RFreception section 101 to a pilot signal and a data signal. Then,demultiplexing section 102 outputs the pilot signal to DFT section 103and outputs the data signal to DFT section 104.

DFT section 103 performs DFT processing on the pilot signal receivedfrom demultiplexing section 102 to convert a time domain signal into afrequency domain signal. Then, DFT section 103 outputs the pilot signalconverted into a frequency domain to demapping section 105.

Demapping section 105 extracts a pilot signal corresponding to thetransmission band of terminal apparatus 200 (described later) from thefrequency-domain pilot signal received from DFT section 103, and outputsthe pilot signal to channel estimation section 107.

Channel estimation section 107 estimates frequency variation in achannel (i.e. channel frequency response) and reception quality perfrequency band by performing correlation calculation on the receptionpilot signal received from demapping section 105 and the transmissionpilot signal that is known between base station apparatus 100 andterminal apparatus 200. Then, channel estimation section 107 outputs achannel estimation value, which is a result of this estimation, tofrequency domain equalization section 108 and scheduling section 113.

DFT section 104 performs DFT processing on the data signal received fromdemultiplexing section 102 to convert a time domain signal into afrequency domain signal. Then, DFT section 104 outputs the data signalconverted into a frequency domain to demapping section 106.

Demapping section 106 extracts part of the data signal corresponding tothe transmission band of terminal apparatus 200 from the signal receivedfrom DFT section 104, and outputs the data signal to frequency domainequalization section 108.

Frequency domain equalization section 108 performs equalizationprocessing on the data signal received from demapping section 106 usingthe channel estimation value (i.e. channel frequency response) receivedfrom channel estimation section 107. Then, frequency domain equalizationsection 108 outputs the signal obtained by equalization processing toIDFT section 109.

IDFT section 109 performs IDFT processing on the data signal input fromfrequency domain equalization section 108. Then, IDFT section 109outputs the signal obtained by IDFT processing to demodulation section110.

Demodulation section 110 performs demodulation processing on the signalreceived from IDFT section 109 and outputs the signal obtained bymodulation processing to decoding section 111.

Decoding section 111 performs decoding processing on the signal receivedfrom demodulation section 110, and extracts the reception data.

Frequency assigning parameter setting section 112 maintains informationabout the relationship between the number of clusters and the frequencyassignment unit that are applied to a terminal to which frequency isassigned. Frequency assigning parameter setting section 112, forexample, maintains a table showing correspondence of a plurality ofnumbers of clusters and frequency assignment units corresponding to eachnumber of clusters. Then, frequency assigning parameter setting section112 sets a frequency assignment unit corresponding to the number ofclusters indicated by the input information about the number ofclusters, to scheduling section 113. This setting processing on afrequency assignment unit basis is performed for each terminal to whichfrequency is assigned. That is, frequency assigning parameter settingsection 112 adjusts a frequency assignment unit to be set to schedulingsection 113 based on the number of clusters to apply to a terminal towhich frequency is assigned.

Here, a frequency assignment unit varies depending on the number ofclusters. Further, an upper limit value is determined for the number ofclusters to apply to a terminal to which frequency is assigned. In thisregard, the relationship between the number of clusters and thefrequency assignment unit that are applied to a terminal to whichfrequency is assigned is determined in advance for each base stationapparatus 100 or the whole system. This relationship will be describedin detail later.

Scheduling section 113 assigns a frequency resource to a terminal towhich frequency is assigned, based on the frequency assignment unit setby frequency assigning parameter setting section 112. Specifically,scheduling section 113 performs frequency scheduling for an arbitraryterminal to which frequency is assigned, based on the reception qualityinformation, in each sub-band of a predetermined transmission band,about a signal transmitted in the predetermined transmission band fromthe arbitrary terminal to which frequency is assigned, which is receivedfrom channel estimation section 107, and the frequency assignment unitthat is received from frequency assigning parameter setting section 112and is applied to the arbitrary terminal to which frequency is assigned.Reporting of frequency scheduling information is performed, as describedabove, by a frequency assigning bit sequence corresponding to anarrangement pattern of the assignment sub-band that is assigned to aterminal to which frequency is assigned and the non-assignment sub-bandthat is not assigned, in a plurality of sub-bands that are formed bydividing the system band per frequency assignment unit.

Encoding section 114 encodes transmission data including the frequencyscheduling information for a terminal to which frequency is assigned,and outputs the encoded data to modulation section 115.

Modulation section 115 modulates the encoded data received from encodingsection 114 and outputs the modulated signal to RF transmission section116.

RF transmission section 116 performs transmission processing, such asD/A conversion, up-conversion, and amplification, on the modulatedsignal received from modulation section 115, and transmits the obtainedradio signal to terminal apparatus 200 via the antenna.

FIG. 4 is a block diagram showing a configuration of terminal apparatus200 according to Embodiment 1 of the present invention. In FIG. 4,terminal apparatus 200 is provided with RF reception section 201,demodulation section 202, decoding section 203, frequency assigningparameter setting section 204, scheduling information setting section205, encoding section 206, modulation section 207, DFT section 208,mapping section 209, IDFT section 210, and RF transmission section 211.

RF reception section 201 performs reception processing, such asdown-conversion and A/D conversion, on a signal received via an antenna,and outputs the reception-processed signal to demodulation section 202.

Demodulation section 202 performs equalization processing anddemodulation processing on the signal received from RF reception section201, and outputs the signal thus processed to decoding section 203.

Decoding section 203 performs decoding processing on the signal receivedfrom demodulation section 202 and extracts control data includingreception data and frequency scheduling information.

Encoding section 206 encodes transmission data and outputs the obtainedencoded data to modulation section 207.

Modulation section 207 modulates the encoded data received from encodingsection 206 and outputs the data-modulated signal to DFT section 208.

DFT section 208 performs DFT processing on the data-modulated signalreceived from modulation section 207 and outputs the obtained frequencydomain data signal to mapping section 209.

Mapping section 209 maps the data signal received from DFT section 208to a frequency domain resource according to the frequency assignmentinformation received from scheduling information setting section 205,and outputs the obtained signal to IDFT section 210.

Frequency assigning parameter setting section 204 extracts informationabout the number of clusters contained in the control data received fromdecoding section 203. Further, frequency assigning parameter settingsection 204 maintains a table showing correspondence that is similar tothe table maintained in frequency assigning parameter setting section112 in base station apparatus 100. Then, frequency assigning parametersetting section 204 outputs a frequency assignment unit corresponding tothe number of clusters indicated by the extracted information about thenumber of clusters, to scheduling information setting section 205.

Scheduling information setting section 205 extracts the frequencyassignment information contained in the control data received fromdecoding section 203. Then, scheduling information setting section 205determines frequency scheduling information for terminal apparatus 200based on the extract frequency assignment information and the frequencyassignment unit received from frequency assigning parameter settingsection 204. Specifically, scheduling information setting section 205reads the frequency assignment information reported from base stationapparatus 100, per frequency assignment unit received from frequencyassigning parameter setting section 204, and determines whether or notthe information is the actual frequency assignment information to beused by terminal apparatus 200. Then, scheduling information settingsection 205 outputs the frequency assignment information for terminalapparatus 200 to mapping section 209.

IDFT section 210 performs IDFT processing on the signal received frommapping section 209. Then, IDFT section 210 outputs the signal obtainedby IDFT processing to RF transmission section 211.

RF transmission section 211 performs transmission processing, such asD/A conversion, up-conversion, and amplification, on the signal receivedfrom IDFT section 210, and transmits the obtained radio signal to basestation apparatus 100 via the antenna.

Then, information about the relationship between the number of clustersand the frequency assignment unit that are applied to a terminal towhich frequency is assigned, which is maintained in frequency assigningparameter setting section 112, will be described below.

FIG. 5 shows an example of a table showing correspondence of a pluralityof numbers of clusters and frequency assignment units corresponding toeach number of clusters. In FIG. 5, the upper limit value of the numberof clusters is 4. Further, the number of clusters of 1 is excludedbecause the number indicates contiguous frequency transmission. Further,the number of bits of frequency assignment information (i.e. the numberof bits forming a frequency assigning bit sequence) is constantregardless of the number of clusters.

Here, the upper limit value of the number of clusters is set based onthe relationship between the number of clusters and system throughputperformance. FIG. 6 shows the relationship between the maximum number ofclusters that can be transmitted by a terminal apparatus and the averagesector throughput (see Non-Patent Literature 3). FIG. 6 shows thatsystem throughput performance does not deteriorate even when the numberof clusters is limited to around 3 to 4. This is because the probabilitythat the number of clusters of a terminal becomes 4 or greater is low.As described above, because the influence on system throughputperformance is small, it is possible to set the upper limit value to thenumber of clusters.

Further, a frequency assignment unit corresponding to each number ofclusters is determined as described below. First, a reference number ofclusters, which constitutes a standard, is determined. As a referencenumber of clusters, the number of clusters that is most frequently usedis selected, for example. Then, when the reference number of clusters isselected, the number of signaling bits that is required to reportfrequency resource assignment information is set as the reference numberof bits. Then, for the number of clusters apart from the referencenumber of clusters, the frequency assignment unit having the closestnumber of signaling bits to the reference number of bits is selected,the number of signaling bits being required to report frequency resourceassignment information using that number of clusters.

FIG. 7 shows a method of determining a frequency assignment unitcorresponding to each number of clusters. Each point in FIG. 7 isplotted based on equation 3 below.[3]The number of signaling bits=┌ log₂(_(┌N) _(RB) _(/P┐+1) C _(2N)_(Cluster) )┐[bits]  (Equation 3)where a system bandwidth is expressed N_(RB) [RB], the number ofclusters is expressed as N_(Cluster), and a frequency assignment unit isexpressed as P [RB].

FIG. 7 shows a graph of the relationship of the number of clusters andthe number of signaling bits when N_(RB)=100 [RB] is satisfied. Assumingthat the number of signaling bits of 18 [bits], in the case of thenumber of clusters of 2 and P=2 [RB], is set as the reference number ofbits, a frequency assignment unit of 4 having the closest number ofsignaling bits to the reference number of bits 18 is selected when thenumber of clusters is 3, and, similarly, a frequency assignment unit of5 is selected when the number of clusters is 4.

FIG. 7 shows the number of signaling bits when the above-describedconventional technique is used, in which the number of signaling bits isfixed (the number of signaling bits is 25 bits in the case of P=4)regardless of the number of clusters. As is clear from FIG. 7, bylimiting the maximum number of clusters to 4 according to the presentembodiment, it is possible to reduce the number of signaling bitscompared to the conventional technique.

Further, by making the numbers of signaling bits the same for eachnumber of clusters, it is possible to use one signaling formatregardless of the number of clusters. By this means, terminal apparatus200 can reduce the number of blind decoding processing for detecting asignaling format.

As described above, according to the present embodiment, in base stationapparatus 100, scheduling section 113 assigns a frequency resource to aterminal to which frequency is assigned, based on the set frequencyassignment unit, and frequency assigning parameter setting section 112adjusts a frequency assignment unit to set to scheduling section 113based on the number of clusters to be applied to the terminal to whichfrequency is assigned.

By doing so, it is possible to perform assignment of a frequencyresource based on the frequency assignment unit optimized with respectto the number of signaling bits for each number of clusters. As a resultof this, it is possible to reduce the amount of signaling for frequencyresource assignment information. Further, by setting the number ofclusters, which is a parameter having little influence on systemthroughput, as a setting parameter of the frequency assignment unit, itis possible to maintain the system throughput.

Further, the number of bits forming a frequency assigning bit sequenceis constant regardless of the number of clusters.

By doing so, it is possible to report frequency resource assignmentinformation using a common signaling format regardless of the number ofclusters. By this means, it is possible to reduce the number of blinddecoding processing for detecting a signaling format at a side receivingscheduling information.

A case has been described with the above description where the number ofbits forming a frequency assigning bit sequence is constant regardlessof the number of clusters. However, the number of bits forming afrequency assigning bit sequence can vary depending on the number ofclusters. In such a case, encoding section 114 makes the total number ofbits constant regardless of the number of clusters by adding paddingbits (for example, a bit value of 0) before encoding a frequencyassigning bit sequence. For example, as shown in FIG. 8, whendetermining the frequency assignment units and the numbers of signalingbits for the numbers of clusters of 3 and 4 by setting the number ofsignaling bits (=22 [bits]) in the case of the number of clusters of 2as the reference number of bits, the numbers of signaling bits requiredfor reporting frequency assignment information are not equal. In thiscase, because encoding section 114 adds a padding bit to make thenumbers of signaling bits equal, it is possible to share a signalingformat, making it possible to reduce the number of blind decodingprocessing for detecting a signaling format at a side receivingscheduling information.

Embodiment 2

A case will be described here with Embodiment 2 where, as a parameter todetermine a frequency assignment unit, a “system bandwidth” is adoptedin addition to the number of clusters.

FIG. 9 is a block diagram showing a configuration of base stationapparatus 300 according to Embodiment 2 of the present invention. InFIG. 9, base station apparatus 300 is provided with frequency assigningparameter setting section 301.

Frequency assigning parameter setting section 301 maintains informationabout the relationship between the number of clusters and the frequencyassignment unit that are applied to a terminal to which frequency isassigned, per system bandwidth. Frequency assigning parameter settingsection 301 has, for example, a second table showing correspondenceshown in FIG. 10 in addition to the first table showing correspondenceshown in FIG. 5. The system bandwidths to be used for the first tableshowing correspondence and the second table showing correspondence aredifferent. Here, the term “system bandwidth” refers to a bandwidth ofthe whole band that base station apparatus 300 can receive, that is, abandwidth of the whole band that can be assigned to terminals in thecell covered by base station apparatus 300.

Then, in the table showing correspondence corresponding to the systembandwidth to be input, frequency assigning parameter setting section 301sets a frequency assignment unit according to the number of clustersindicated by the information about the number of clusters to be input,to scheduling section 113. Frequency assigning parameter setting section301, for example, uses the first table showing correspondence shown inFIG. 5 when the system bandwidth is 100 [RB], and uses the second tableshowing correspondence shown in FIG. 10 when the system bandwidth is 200[RB]. That is, frequency assigning parameter setting section 301switches tables showing correspondence to be used depending on thesystem bandwidth.

Here, when the system bandwidth varies, usage rate per number ofclusters of a terminal apparatus in the system changes. For example,because the amount of frequency resource that can be used by oneterminal apparatus changes as the system bandwidth is broadened, it isnecessary to assign larger number of clusters to a terminal apparatus toimprove throughput performance.

Therefore, frequency assigning parameter setting section 301 switchestables showing correspondence to be used depending on the systembandwidth, so that it is possible to use the optimal table showingcorrespondence according to the system bandwidth.

FIG. 11 is a block diagram showing a configuration of terminal apparatus400 according to Embodiment 2 of the present invention. In FIG. 11,terminal apparatus 400 is provided with frequency assigning parametersetting section 401.

Frequency assigning parameter setting section 401 extracts informationabout the number of clusters and information about a system bandwidththat are contained in the control data received from decoding section203. Further, frequency assigning parameter setting section 401maintains a table showing correspondence that is similar to the tablemaintained in frequency assigning parameter setting section 301 of basestation apparatus 300. Then, frequency assigning parameter settingsection 401 outputs a frequency assignment unit corresponding to thesystem bandwidth indicated by the extracted information about a systembandwidth and the number of clusters indicated by the information aboutthe number of clusters, to scheduling information setting section 205.

As described above, according to the present embodiment, in base stationapparatus 300, frequency assigning parameter setting section 301 adjuststhe frequency assignment unit to be set based on the bandwidth of thesystem band in addition to the number of clusters.

By doing so, it is possible to use the optimum relationship between thenumber of clusters and the frequency assignment unit corresponding tothe system bandwidth, making it possible to improve system throughputperformance.

Embodiment 3

A case will be described here with Embodiment 3 where, when the numberof bits forming a frequency assigning bit sequence varies depending onthe number of clusters, offset information for fine-tuning the frequencyassignment position is added, without padding “0” bits.

FIG. 12 is a block diagram showing a configuration of base stationapparatus 500 according to Embodiment 3 of the present invention. InFIG. 12, base station apparatus 500 is provided with frequency assigningparameter setting section 501 and scheduling section 502.

Frequency assigning parameter setting section 501 determines whether ornot to shift the frequency resource assigned in scheduling section 502,in a direction of frequency, based on the channel estimation valuereceived from channel estimation section 107. The standard for decidingwhether or not to perform shifting is based on the channel quality inthe RB to be assigned. For example, the RB to be assigned having ahigher average SINR is selected by calculating average SINRs in the RBsto be assigned for the cases where shifting is performed and notperformed. By this means, because it is possible to assign the RB havinga higher channel quality to a terminal, it is possible to improve systemthroughput performance.

Scheduling section 502 forms a frequency assigning bit sequence asscheduling section 113 does. Further, scheduling section 502 adds offsetinformation to a frequency assigning bit sequence according to theresult of determination in frequency assigning parameter setting section501. For example, as shown in FIG. 13, the bit value of 0 is set asoffset information when determination not to perform shifting is made,while the bit value of 1 is set as offset information when shifting isperformed. An example of a table showing correspondence in this case isshown in FIG. 14.

As described above, according to the present invention, in base stationapparatus 500, frequency assigning parameter setting section 501determines whether or not to shift the frequency resource assigned inscheduling section 502, in a direction of frequency, based on thechannel estimation value, and scheduling section 502 adds offsetinformation to a frequency assigning bit sequence corresponding to theresult of determination in frequency assigning parameter setting section501.

By doing so, the flexibility in frequency scheduling increases, so thatit is possible to accurately assign frequency resources having goodchannel quality, making it possible to improve system throughputperformance.

Other Embodiment

(1) In the above embodiments, it is possible to switch methods ofreporting frequency scheduling information according to the number ofclusters between either method of Embodiments 1 to 3 and a conventionalmethod (i.e. a method of reporting in the bitmap format). For example,as shown in FIG. 15, it is possible to apply either method ofEmbodiments 1 to 3 when the number of clusters is 4 or smaller, and toapply the conventional method when the number of clusters is 5 orgreater.

(2) In the above embodiments, when the number of clusters to report isnot a power of 2, it is possible to report identification informationusing a pattern combining the number of clusters and frequencyassignment information. For example, as shown in FIG. 16, by reportingidentification information using the pattern combining the number ofclusters and frequency assignment information, it is possible to reducethe number of the overall signaling bits for the number of clusters andfrequency assignment information. Comparison of FIG. 16 with FIG. 8shows that, in the case of the number of clusters of 3, it is possibleto reduce the overall signaling bits for the number of clusters andfrequency assigning information by one bit. By assigning this reducednumber of bits to offset information, it is possible to increase theflexibility in frequency scheduling, making it possible to improvesystem performance.

(3) Although cases have been described with the above embodiments wherethe case of the number of clusters of 1 is excluded, it is possible toinclude the number of clusters of 1 (contiguous frequency assignment).For example, as shown in FIG. 17, by sharing a common signaling formatin both contiguous frequency assignment and non-contiguous frequencyassignment, it is possible to reduce the number of blind decodingprocessing for detecting a signaling format at a side receivingscheduling information.

(4) Also, although cases have been described with the above embodimentsas examples where the present invention is configured by hardware, thepresent invention can also be realized by software.

Each function block employed in the description of each of theaforementioned embodiments may typically be implemented as an LSIconstituted by an integrated circuit. These may be individual chips orpartially or totally contained on a single chip. “LSI” is adopted herebut this may also be referred to as “IC,” “system LSI,” “super LSI,” or“ultra LSI” depending on differing extents of integration.

Further, the method of circuit integration is not limited to LSI's, andimplementation using dedicated circuitry or general purpose processorsis also possible. After LSI manufacture, utilization of a programmableFPGA (Field Programmable Gate Array) or a reconfigurable processor whereconnections and settings of circuit cells within an LSI can bereconfigured is also possible.

Further, if integrated circuit technology comes out to replace LSI's asa result of the advancement of semiconductor technology or a derivativeother technology, it is naturally also possible to carry out functionblock integration using this technology. Application of biotechnology isalso possible.

The disclosure of Japanese Patent Application No. 2009-035617, filed onFeb. 18, 2009, including the specification, drawings and abstract, isincorporated herein by reference in its entirety.

INDUSTRIAL APPLICABILITY

A scheduling apparatus and a scheduling method according to the presentinvention is useful for maintaining system throughput performance andreducing the amount of signaling for frequency resource assignmentinformation.

The invention claimed is:
 1. A base station apparatus comprising: asetting section configured to set a resource block group size forallocating one or more frequency resources for a user equipmentaccording to both a system bandwidth and a number of clusters which is anumber of frequency resources allocated to the user equipment, whereinthe resource block group size is a number of resource blocks included ina resource block group, each of the clusters comprises one or moreresource block groups of the resource block group size, and each clusteris located on a separate position from other clusters on a frequencyaxis; and a scheduler configured to allocate one or more frequencyresources to the user equipment, in one or more units of the resourceblock group size that is set by the setting section.
 2. The base stationapparatus according to claim 1, wherein a common signaling format isused for both continuous frequency resource allocation in a case wherethe number of clusters is one, and non-continuous frequency resourceallocation in a case where the number of clusters is two or more.
 3. Thebase station apparatus according to claim 2, wherein the commonsignaling format includes a type bit indicative of the number ofclusters and allocation information indicative of the frequency resourceallocation.
 4. The base station apparatus according to claim 3, whereinthe allocation information has N bits calculated according to afollowing equation:N=┌ log₂((┌N _(RB) /P┐+1)C(2N_(Cluster)))┐ wherein, N_(RB) is the systembandwidth, P is the resource block group size, N_(Cluster) is the numberof clusters, and C means a number of combinations of selecting2*N_(Cluster) cluster starting and ending positions out of ┌N_(RB)/P┐+1number of possible cluster starting and ending positions.
 5. The basestation apparatus according to claim 3, wherein the type bit isindicative of a restricted number of clusters.
 6. The base stationapparatus according to claim 1, wherein a total number of bits in asignaling format used for continuous frequency resource allocation in acase where the number of clusters is one is equal to a total number ofbits in a signaling format used for non-continuous frequency resourceallocation in a case where the number of clusters is two or more.
 7. Thebase station apparatus according to claim 1, wherein the resource blockgroup size is set to a larger number as the number of clusters islarger.
 8. A scheduling method performed by a base station apparatuscomprising: setting a resource block group size for allocating one ormore frequency resources for a user equipment according to both a systembandwidth and a number of clusters which is a number of frequencyresources allocated to the user equipment, wherein the resource blockgroup size is a number of resource blocks included in a resource blockgroup, each of the clusters comprises one or more resource block groupsof the resource block group size, and each cluster is located on aseparate position from other clusters on a frequency axis; allocatingone or more frequency resources to the user equipment, in one or moreunits of the resource block group size.
 9. The scheduling method ofclaim 8 wherein a common signaling format is used for both continuousfrequency resource allocation in a case where the number of clusters isone, and non-continuous frequency resource allocation in a case wherethe number of clusters is two or more.
 10. The scheduling method ofclaim 9 wherein the common signaling format includes a type bitindicative of the number of clusters and allocation informationindicative of the frequency resource allocation.
 11. The schedulingmethod of claim 10 wherein the allocation information has N bitscalculated according to a following equation:N=┌ log₂((┌N _(RB) /P┐+1)C(2N_(Cluster)))┐ wherein, N_(RB) is the systembandwidth, P is the resource block group size, N_(Cluster) is the numberof clusters, and C means a number of combinations of selecting2*N_(Cluster) cluster starting and ending positions out of ┌N_(RB)/P┐+1number of possible cluster starting and ending positions.
 12. Thescheduling method of claim 10 wherein the type bit is indicative of arestricted number of clusters.
 13. The scheduling method of claim 8wherein a total number of bits in a signaling format used for continuousfrequency resource allocation in a case where the number of clusters isone is equal to a total number of bits in a signaling format used fornon-continuous frequency resource allocation in a case where the numberof clusters is two or more.
 14. The scheduling method according to claim8, wherein the resource block group size is set to a larger number asthe number of clusters is larger.